2014 Chocorua Lake Water Quality Results

2014 Water Quality Results:

by Dwight Baldwin

Water quality data was collected by Conservancy volunteers between May 8 and 11, 2014 at the deep Chocorua Lake sampling station. Overall, the 2014 seasonal water transparency in Chocorua Lake was high, the amount of microscopic plant algal growth (greenness) was low to moderate, and the phosphorus (nutrient) concentrations were low and reflected the conditions considered typical of an unproductive New Hampshire lake.  Funding for the water quality monitoring program in Chocorua Lake was provided by the Conservancy.  The Chocorua Lake Conservancy has been participating in the New Hampshire Lakes Lay Monitoring Program since 1981.

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Long Term Trends:

  • Water Clarity:  Water clarity, measured as Secchi disk depth, decreased between 1982 and 2014.  Water transparency data collected before (1982‐1999) and after (2000‐2014) the implementation of erosion control measures along the Route 16 travel corridor both display a trend of decreasing water clarity; however, the amount of decline over time has decreased since the Conservancy’s installation of the erosion-control practices.

  • Chlorophyll: Chlorophyll a, a measure of microscopic plant life within the lake, increased between 1982 and 2014. An examination of the chlorophyll data collected before and after the installation of erosion control measures along the Route 16 travel corridor indicates the water quality has improved in recent years. The chlorophyll a concentrations increased by approximately 2.0 parts per billion (ppb) between 1982 and 1999 while the chlorophyll a concentrations documented between 2000 and 2014, following the installation of erosion control measures, have stabilized.

  • Total Phosphorus:  Phosphorus is the nutrient most responsible for microscopic plant growth.  The long‐term total phosphorus data display a trend of decreasing concentrations between 1999 and 2014.  Total phosphorus data were not collected consistently prior to the 1999 sampling season.

  • Color: Color is a result of naturally occurring “tea” color substances from the breakdown of soils and plant materials. Color has varied annually and displays a relatively stable trend between 1986 and 2014.

Banner: Beneath the surface of the lake. Photo: Pen Hallowell